Fibroblasts have been used previously in an attempt to cure genetic disease. HLA-matched fibroblasts from normal donors were subcutaneously injected into patients suffering from various forms of mucopolysaccharidosis (MPS). Mannich, A., et al., Pediatr. Res. 16: 259-260, 1982; Dean, M. F., et al., Pediatr. Res. 16: 260-261, 1982. Although the normal fibroblasts were able to reverse the accumulation of metabolic intermediates in tissue culture, there were only minor, transient alterations in metabolic products in the patients' serum, and there were no changes in the patients' overall condition. The fibroblasts in these experiments produced only normal levels of enzyme and may have been subject to graft rejection. In addition, it is not known if the pathophysiological effects of the enzyme deficiency in MPS patients are reversible.
Studies on transfer and expression of genes in human fibroblasts have been severely limited by the short in vitro replicative life span of normal human diploid fibroblast cells and by inefficient gene transfer techniques. Debenham, P. G., et al., Int. J. Radiat. Biol. 45: 525-536, 1984; Yoakum, G. H., et al., Science 222: 385-389, 1983.
Retrovirus vectors offer an alternative for gene transfer. Amphotropic murine retroviruses can infect immortalized human fibroblast cells (Miller, A. D., et al., Proc. Natl. Acad. Sci. USA 80: 4709-4713, 1983), but it is not known whether retroviral infection of normal human fibroblasts would be inhibited due to their different growth characteristics. This issue is important since many human genetic diseases such as oncogenic transformation exhibit phenotypes that are masked in immortalized cells.